Transmission Definitions

GENERAL INFORMATION
The following definitions are provided to establish a common language and assist the user in describing transmission related conditions. Some of these terms or conditions are used in the transmission diagnosis section.

THROTTLE POSITIONS
Minimum Throttle - least amount of throttle opening required for an upshift.
Light Throttle - approximately 1/4 of accelerator pedal travel.
Medium Throttle - approximately 1/2 of accelerator pedal travel.
Heavy Throttle - approximately 3/4 of accelerator pedal travel.
Wide Open Throttle (WOT) - full travel of accelerator pedal.
Full Throttle Detent Downshift - quick application of accelerator pedal to its full travel, forcing a downshift.
Zero Throttle Coastdown - full release of accelerator pedal while vehicle is in motion in drive range.
Engine Braking - condition where engine is used to slow vehicle by manually downshifting during zero throttle coastdown.

SHIFT CONDITIONS
Bump - sudden and forceful application of clutch or band.
Chuggle - bucking or jerking condition that may be engine related. May be most noticeable when file torque converter clutch is engaged. Similar to the feel of towing a trailer.
Delayed - condition where shift is expected but does not occur for a period of time. Examples of this condition could be described as clutch or band engagement that does not occur as quickly as expected during part throttle or wide open throttle, or when manually downshifting to lower range. Also defined as "late', or"extended."
Double Bump - two sudden and forceful applications of clutch or band. Also defined as "double feel."
Early - condition where shift occurs before vehicle has reached proper speed and tends to labor engine after upshift.
End Bump - firmer feel at end of shift as compared to feel at start of shift. Also defined as "end feel" or "slip bump."
Firm - noticeable quick application of clutch or band that is considered normal with medium to heavy throttle shift. Should not be confused with "harsh" or "rough."
Flare - quick increase in engine -RPM accompanied with momentary loss of torque. This most generally occurs during a shift. Also defined as "slipping."
Harsh - more noticeable application of clutch or band as compared to "firm." This condition is considered undesirable at any throttle position. Also defined as "rough."
Hunting - repeating quick series of upshifts and downshifts causing noticeable change in engine RPM. An example could be described as a 4-3-4 shift pattern. Also defined as "busyness."
Initial Feel - distinct firmer feel at start of shift as compared to finish of shift.
Late - shift that occurs when engine is at higher than normal RPM for given amount of throttle.
Shudder - repeating jerking sensation similar to "chuggle" but more severe and rapid in nature. This condition may be most noticeable during certain ranges of vehicle speed. May also be used to define the condition after torque converter clutch engagement.
Slipping - noticeable increase in engine RPM without vehicle speed increase. Slip usually occurs during or after initial clutch or band engagement.
Soft - slow, almost unnoticeable clutch application with very little shift feel.
Surge - repeating engine related feeling of acceleration and deceleration that is less intense than chuggle.
Coup - condition where two opposing clutches are attempting to apply at the same time causing the engine to labor with noticeable loss of engine RPM.

NOISE CONDITIONS
Gear Noise - whine, most noticeable in first gear and reverse that is related to vehicle speed. A gear noise condition may become less noticeable or go away after an upshift.
Pump Noise - high-pitched whine increasing in intensity with engine RPM. This condition may also be noticeable in "PARK" and "NEUTRAL" operating ranges with the vehicle stationary.